Sa-Sm

 

SAA

Abbrevation for Satellite Active Archive, a digital library of real-time and historical satellite data from NOAA's POES. SAA allows users to search inventories of satellite data, preview representative Earth images of that data, and to download the data for further processing and analysis. See the SAA Web site.

 

Saale

The American name for the glacial period starting about 350,000 years ago and lasting about 150,000 years. It featured extensive ice cover over the northlands and the Arctic Ocean. This period is known as Riss in the Alpine scheme and Illinoian in the Scandinavian scheme. The was preceded by the Kansan period and followed by the Warthe-Weischel period.

 

SAARI

Acronym for the South Atlantic Accelerated Research Initiative, an ONR research program primarily directed toward improvement of the description of the subtropical South Atlantic. It focused on the poleward corners of the subtropical gyre, i.e. the separation of the Brazil Current and its confluence with the Malvinas or Falkland Current in the southwest, and the Agulhas Retroflection and Benguela Current in the southeast. See Gordon (1988).

 

SABRE

Acronym for South Atlantic Bight Recruitment Experiment, a NOAA program to stud the birthdate history of survivors (larvae, late larvae, and juveniles) to determine which life history phase or passage (spawning, transport across the shelf, inlet ingress, estuarine development, inlet egress) regulates recruitment variability in annual cohorts of transgressive species like Atlantic menhaden. See the SABRE Web site.

 

SACCF

Abbreviation for the Southern ACC Front.

 

SADCO

Acronym for the South African Data Centre for Oceanography, a center that stores, retrieves and manipulates multi-disciplinary marine information from the areas around Southern Africa. See the SADCO Web site.

 

SAFARI

Acronym for Southern African Fire-Atmosphere Research Initiative, a BIBEX program.

 

SAFIRE

Acronym for Spectroscopy of the Atmosphere Using Far Infrared Emission.

 

SAGE

Acronym for Stratospheric Aerosol and Gas Experiment.

 

salinity

In oceanography, the salinity of sea water is a measure of the amount of dissolved salts expressed as the number of grams of dissolved material in one kilogram of sea water. It is more strictly defined as the weight in grams of the dissolved inorganic matter in 1 kg of sea water after all bromide and iodide have been replaced by the equivalent amount of chloride, and all carbonate converted to oxide. In practice it is determined from conductivity and temperature measurements in the laboratory or from conductivity, temperature and pressure measurements in situ via the use of a CTD. See Riley and Chester (1971).

 

SALMON

Abbreviation for Sea Air Land Modeling Operational Network, a project whose purpose is to develop from three existing models (ocean, river and groundwater) a single model able to handle the description of environmental quality in a whole system of regional scale including marine, river, groundwater and atmospheric inputs. SALMON is a project of the Center for Environmental Studies at the University of Liege in Belgium. See the SALMON Web site.

 

SALR

Abbreviation for saturated adiabatic lapse rate.

 

SALSA

Acronym for Semi-Arid Land Surface-Atmosphere Program, a long-term multidisciplinary monitoring and modeling effort for the Upper San Pedro River Basin of southeastern Arizona and northern Sonora, Mexico. See the SALSA Web site.

 

salt fingering

See double diffusive instability.

 

salt fountain

A hypothesized perpetual fountain where a long, narrow heat-conducting pipe inserted vertically through a region of ocean where warm, salty water overlies colder, fresher (and therefore denser) water. Water pumped upwards through the pipe would reach the same temperature as the surroundings at the same level (by conduction of heat through the wall of the pipe), while it remained fresher and therefore lighter. A fountain started thusly (in either direction) will continue to flow so long as there is a vertical gradient of salinity to supply potential energy. The idea was first advanced by Stommel et al. (1956) and is discussed in Turner (1973).

 

sample

In signal processing, to pick out values from an analog signal, usually at regular intervals, to create a corresponding digital signal.

 

SAMW

Abbreviation for Subantarctic Mode Water.

 

Sandstrom Theorem

An ocean circulation theorem that states that a closed steady circulation can only be maintained in the ocean if the heat source is situated at a lower level than the cold source. See Defant (1961).

 

SANTA CLAuS

Acronym for Studies in ANTarcticA Coupled Linkages Among micro (U) organismS, a special focus microbiology process cruise designed and organized to focus on the trophic coupling among various microbial assemblages including heterotrophic bacteria, archaeobacteria, phytoplankton, protozoans and viruses. See the SANTA CLAuS Web site.

 

Santonian

The fourth of six ages in the Late Cretaceous epoch, lasting from 87.5 to 84.0 Ma. It is preceded by the Coniacian age and followed by the Campanian age.

 

SAR

Abbreviation for Synthetic Aperture Radar, a side-looking imaging radar system that uses the Doppler effect to sharpen the effective resolution in the cross-track direction.

 

Sargasso Sea

A clockwise-circulating region in the North Atlantic Ocean bound by the Gulf Stream on the west and north and less definitely to the east at 40 deg. W near the Canary Current and to the south at 20 deg. N near the North Equatorial Drift Current. It is so named because of the indigenous, yellow-brown seaweed called Sargassum that is found there in great abundance. The Sargasso is part of the subtropical gyre circulation system in the North Atlantic and comprises a large part of its interior circulation, covering an area of around 5.2 million square kilometers.

A large volume of a type of mode water known as 18 deg. water forms in the Sargasso in the winter and is seen as a thick layer of water at that temperature between 250 and 400 m depth. In the summer an excess of evaporation over precipitation results in a thick (nearly 900 m deep near the center) lens of water warmer and more saline than surrounding waters. The anticyclonic sense of the circulation causes this water to pile up such that it is almost a meter higher than the sea level along the eastern U.S. coast. This water lens also serves to inhibit the upwelling of nutrient-rich, colder water which results in a sparsity of marine life in the region. It is has been called the clearest, purest and biologically poorest ocean water ever studied.

The northwestern part of the Sargasso is a region of recirculation for the Gulf Stream. This recirculation region is dominated by cold core eddies pinched off from the Gulf Stream, with as many as 10 clearly identifiable rings found there at any one time. This makes this northwestern region one of the most energetic in the world ocean.

 

Sargassum

The name given to about eight species of seaweed that float in clumps and long windrows in the Sargasso Sea. It was so named by Portuguese sailors who followed the voyages of Columbus through the region and noticed the resemblance of the small air bladders that allow Sargassum to float to a type of grape called Salgazo.

 

saros cycle

A cycle of of 18 years and 11 days after which the centers of the Sun and Moon return to their same relative positions adn the same pattern of eclipses is repeated. It is equal to 223 synodic months, 19 eclipse years, and 239 anomalistic months.

 

SASS

Acronym for the SEASAT-A Scatterometer System, an active backscatter scatterometer operating at a frequency of 13.0 GHz which produced earth locatino and time tagged backscatter coefficients, surface wind stress, and surface wind vectors (with a 180 deg. directional ambiguity).

 

satellite oceanography

More later.

 

satellite/surface temperature inconsistency

This refers to a supposed inconsistency between satellite measurements of global temperature change (via MSU data) and surface measurements of the same. The measured tropospheric and surface temperature changes (from the former and latter, respectively) over the last decade differ by 0.12 to 0.15 , with the tropospheric measurements indicating less warming. The satellite measurements are detailed in Christy and McNider (1994), and a discussion of the reasons for the differences can be found in Hansen et al. (1995). The reasons involve a combination of uncertainties in both types of data as well as the realization that temperature changes need not be the same at all altitudes.

 

saturated adiabatic lapse rate

The temperature lapse rate of air which is undergoing a reversible natural adiabatic process. Abbreviated SALR.

 

saturated humidity mixing ratio

The humidity mixing ratio of air which is saturated at a specified temperature and pressure, with saturation defined with reference to either liquid water or ice.

 

saturation mixing ratio

An atmospheric quantity given by

where is the ratio, the saturation vapor pressure and p the atmosphere pressure.

 

saturation vapor pressure

Usually measured with respect to water, this is the maximum water vapor pressure that can occur when the water vapor is in contact with a free water surface at a particular temperature. It is the water vapor pressure that exists when effective evaporation ceases.

 

SatView

An X-window based tool for viewing satellite images and weather data. See the SatView Web site.

 

SAUW

Abbreviation for Subantarctic Upper Water.

 

SAVE

Acronym for South Atlantic Ventilation Experiment.

 

Savonius rotor

A rotor originally developed for power generation (i.e. it's a propellor in reverse that spins when placed in moving water) that has been extensively used as a sensor on various ocean current meters. Its advantages are that it is rugged, omni-directional and linear in steady flow, but its response to time-varying flow and susceptibility to contamination by vertical flows make it unsuitable for measurements near the surface where wave action creates both time-varying and vertical flow fields. See Heinmuller (1983).

 

Savu Sea

More later.

 

SAZ

Abbreviation for Subantarctic Zone.

 

scale depth

A means of characterizing a (oceanic or atmospheric) density field. It is defined by where c is the speed of sound and g gravitational acceleration. In the ocean this is on the order of 200 km. The largeness of this in comparison to the water depth (5 km) is one of the key assumptions in the Boussinesq approximation.

 

SCAR

Acronym for Scientific Committee on Antarctic Research.

 

SCAR-A

Acronym for Sulfates, Clouds and Radiation - America, an experiment to study how sulfates, clouds, and radiation interact to affect climate. The primary objective is to characterize the relationship between sulfate particles and clouds and gain a better understanding of how sulfates affect the reflective properties of clouds. See the SCAR-A Web site.

 

ScaRaB

Acronym for Scanner for Radiation Budget, a satellite-borne radiometer for Earth radiation budget experiments. ScaRaB measures the radiance at the top of the atmosphere in four channels, i.e. visible, solar, total, and atmospheric window, each of which has a separate telescope on the instrument. The radiation budget parameters are derived from the total and solar channels, while the visible and atmospheric window channels are used for scene identification. See the ScaRaB Web site.

 

scattering

The process by which some of a stream of radiation is dispersed to travel in directions other than that which from it was incident by particles suspended in the medium through which it is travelling.

 

scatterometer

A high-frequency radar instrument that transmits pulses of energy towards the ocean and measures the backscatter from the ocean surface. It detects wind speed and direction over the oceans by analyzing the backscatter from the small wind-induced ripples on the surface of the water. See the NASA JPL scatterometer site.

 

Schlutsky-Yule effect

A consequence of smoothing a time series with a low-pass filter. In a relatively short time series, even purely random fluctuations can give the impression of there being significant quasi-cyclic fluctuations present if they are smoothed by some sort of running mean. This is name for two statisticians who demonstrated in 1927 that some trade cycles that had been apparently discovered in some 19th century data could be reproduced from a series of random numbers. See Burroughs (1992), p. 20.

 

Schmidt number

A nondimensional number that relates the competing effects of gas diffusion and fluid viscosity on the piston velocity, a key variable in measuring gas transfer across the air-sea interface. The Schmidt number is given by

where is the kinematic viscosity and D the molecular diffusivity of gas in sea water. See Najjar (1991).

 

Schwarzchild equation

An equation that shows that it is theoretically possible to determine the intensity of radiation at any point of the atmosphere provided that the distribution of absorbing mass and the absorption coefficients are known. It is given by

where is the intensity at wavelength (power per unit area per unit solid angle per unit wavelength per unit time), the extinction coefficient for radiation at wavelength , and the black body radiation at wavelength . See Peixoto and Oort (1992).

 

SCIAMACHY

Acronym for Scanning Imaging Absorption Spectrometer for Atmospheric Chartography, an instrument for performing global atmospheric measurements. SCIAMACHY comprises a moderately high resolution spectrometer to observed transmitted, reflected, and scattered light from the atmosphere in the ultriaviolet, visible and infrared wavelength regions. It is designed to measure both tropospheric and stratospheric abundances of a number of atmospheric constituents which take part in the ozone layer or the greenhouse effect. See the SCIAMACHY Web site.

 

scirocco

A warm, southerly wind in the Mediterranean region. Near the north coast of Africa the wind is hot and dry and often carries much dust. After crossing the Mediterranean, the scirocco reaches the European coast as a moist wind and is often associated with low stratus.

 

SCOPE

Acronym for Scientific Committee on Problems of the Environment, an ICSU committee.

 

SCOR

Acronym for Scientific Committee on Oceanic Research, an ICSU committee.

 

SCORPIO

A name of a 1973 expedition, led by Henry Stommel, to perform trans-Pacific hydrographic sections at 28 and 43 deg. S. See Stommel et al. (1973).

 

Scotia Ridge

A ridge connecting South American and Antarctica located at about 70 deg. W in the Southern Ocean that, along with the narrowing of the Drake Passage 2000 km to the west, impedes the flow of the Antarctic Circumpolar Current (ACC). It is generally less than 2000 m deep with some openings at the 3000 m level. After the ACC accelerates to squeeze through the Drake Passage it hits to Ridge and an increased speed and shifts northward.

 

Scotia Sea

More later.

 

SEA

Acronym for superposed epoch analysis. See Haurwitz and Brier (1981).

 

sea ice

More later.

 

sea level

Much more later.

 

Sea of Japan

See Japan Sea.

 

sea state

More later.

 

SEASAT

A NASA satellite that operated from June 1978 to October 1978. Instruments on board included SASS, an altimeter, SMMR, a microwave SAR, and VIRR. The altimeter was an active radar altimeter which produced earth location and time-tagged satellite heights, significant wave heights, and geoid information. The SAR produced 25 meter resolution surface roughness imagery on a 100 km wide ground swath.

 

seamount

More later.

 

seasonal thermocline

In oceanography, a weakly stratified layer of water that appears when the mixed layer makes a rapid transition between its winter maximum and its summer mimimum. It is created by deep convection during the winter, and several processes are responsible for its restratification during the rest of the year. These processes, in chronological order starting in early spring, are the creation of a fossil thermocline during the ascent of the mixed layer, solar heating below the mixed layer, geostrophic advection, and thermohaline intrusion.

 

seasonal thermostad

See seasonal thermocline.

 

seawater

More later.

 

SeaWiFS

Acronym for Sea-viewing Wide-Field of view Sensor, an ocean color sensor to study ocean productivity and interactions between the ocean ecosystems and the atmosphere. For more information see the SeaWiFs Web site.

 

Secchi disk

A round, white target with a diameter around 0.25 m that is lowered from a vessel and viewed from above the surface in full solar illumination to estimate the attenuation in the water column. This is done by empirically relating the depth at which the disk disappears to the attenuation. This method was devised in the 1860s by an Italian astronomer named Angelo Secchi who used it while he worked in the Mediterranean aboard the papal vessel Immacolata.

 

SECHIBA

Acronym for Schematisation des Echanges Hydriques a l'Interface entre la Biosphere et l'Atmosphere, an LSP. See Ducoudre et al. (1993).

 

secondary aerosol

One of two types of atmospheric aerosols as classified by formation process, the other being primary aerosols. Secondary aerosols result from particle formation by gas reactions. See Pueschel (1995).

 

sedimentary facies

A stratigraphic facies representing any areally limited sedimentary deposit (as part of a stratigraphic unit) exhibiting lithologic or paleontologic characteristics that differ significantly from one in another part of the same unit. The definition also implies that the ages and the physical locations of the deposits are reasonably close.

 

SEFCAR

Acronym for South Eastern Florida and Caribbean Recruitment, a NOAA program to study the processes regulating the distribution of planktonic larval fish prey along transport pathways connecting offshore spawning sites with local neritic juvenile habitats. See the SEFCAR Web site.

 

seiche

More later.

 

seismic sea wave

Much more later.

 

Seismic Sea-Wave Warning System

A network of seismographs across the Pacific Ocean to serve as an early warning system against the arrival of seismic sea waves (SSW) (also called tsunamis or, in an egregious misnomer, tidal waves). The SSWWS was established in 1946 after a particularly destructive SSW originating at Unimak, Alaska struck Hawaii and killed 159 people. Its headquarters are in Honolulu, Hawaii and it is operated by the Coast and Geodetic Survey of the U.S. Dept. of Commerce.

 

seistan wind

A strong northerly wind that appears in summer in the province of Seistan in eastern Iran. It continues for about four months and as such is known as the ``wind of 120 days''. It occasionally reaches hurricane force, i.e. over 70 mph.

 

Selandian

The second of two ages in the Paleocene epoch (coincidental with the Late Paleocene), lasting from 63.6 to 57.8 Ma. It is preceded by the Danian age and followed by the Ypresian age of the Eocene epoch.

 

semidiurnal

Descriptive of a tide that has a cycle of approximately one-half a tidal day, as opposed to diurnal.

 

semi-geostrophic equations

See G. and Flierl (1981).

 

semi-implicit method

A numerical approximation algorithm that allows longer time steps than an explicit method and is less computationally onerous than a fully implicit method. Algorithms can usually be designed using this compromise method that both allow the longer time step and don't sacrifice numerical accuracy.

 

sensible heat

The portion of total heat associated with a temperature change, as opposed to latent heat. This is so-called because it can be sensed by humans. The sensible heat is calculated by

where values are

for dry air,

for moist air (where r is the mixing ratio of water vapor), and

for liquid water.

 

sensible heat flux

The flux of heat between the ocean surface and atmosphere that results mainly from their difference in temperature. The heat exchange is accompished via molecular conduction in the first few millimeters above the surface and via turbulent mixing and convection above that. The flux is usually from the ocean to the atmosphere during the day and opposite during the evening and night. See Peixoto and Oort (1992).

 

SEQUAL

Acronym for the Seasonal Response to the Equatorial Atlantic research program. See Katz (1987) and Richardson and Reverdin (1987).

 

Serravallian

The fourth of six ages in the Miocene epoch (the second of two in the Middle Miocene), lasting from 15.1 to 11.2 Ma. It is preceded by the Langhian age and followed by the Tortonian age.

 

SESAME

Acronym for the Second European Stratospheric Arctic and Mid-latitude Experiment. See the SESAME Web page.

 

Seven Seas

A term used long ago to collectively refer to the Indian Ocean, the Red Sea, the Persian Gulf, the Black Sea, the Sea of Azov, the Adriatic Sea and the Caspian Sea. The term is no longer much used although it is generally conceded that a modern and more geographically generous grouping would be the Arctic Ocean, the Southern Ocean, the Indian Ocean, the North and South Atlantic Ocean and the North and South Pacific Ocean.

 

SGCS

Abbreviation for Standard Global Chronostratigraphic Scale. See Standard Stratigraphic Scale.

 

SGGCM

Abbreviation for WCRP Steering Group on Global Climate Modelling.

 

SGM

Abbreviation for the satellite-gauge-model technique, a method of combining data from satellites, output from numerical models and ground-based precipitation measurements to obtain global precipitation fields as well as error estimates. See Huffman et al. (1995).

 

SH

Abbreviation for southern hemisphere.

 

shallow atmosphere approximation

In meteorology, an approximation made to simplify the equations of motion in spherical coordinates where the radial distance r is replaced by a+z, where the altitude z is much smaller than the radius of the Earth r. See Salby (1992).

 

shallow water approximation

In oceanography, an approximation made for motions where the aspect ratio, defined as the ratio of the vertical and horizontal length scales, is small. An example arises in the study of the tides, where the horizontal scale of the wave motion is thousands of kilometers and the vertical scale in constrained by the maximum depth of the oceans, and as such the applicable dynamics are those of shallow water gravity waves, i.e. gravity waves the ``feel'' and are influenced by the bottom. See Muller (1995).

 

shamal

A northwesterly wind which blows in summer over Iraq and the Persian Gulf. It is strong during the day and decreases at night.

 

SHEBA

Acronym for the Surface Heat Budget of the Arctic project, a WCRP program to address the interaction of the surface energy balance, atmospheric radiation, and clouds over the Arctic Ocean. See the SHEBA Web site.

 

SHF

Abbreviation for super high frequency, an electromagnetic spectrum waveband ranging from 3 to 30 GHz.

 

shield

See the synonymous craton.

 

SI

Abbreviation for Systeme Internationale.

 

SiB

Abbreviation for Simple Biosphere Model, a model designed for use in GCMs to describe the climatologically important interactions between the terrestrial biosphere and the atmosphere. It assembles information about particular vegetation types to describe their average physical, morphological and physiological states at different times throughout the year. These vegetation types are assigned to a given grid area to obtain upper (canopy), lower (groundcover), both or neither level(s) and are combined with atmospheric boundary conditions (air temperature, vapor pressure, wind speed, precipitation, etc.) to calculate the fluxes of heat, water vapor, momentum and radiation between the surface and the atmosphere. See Sellers et al. (1986) and Dorman and Sellers (1989) for futher details.

 

sidereal day

The interval of time between successive passages of the vernal equinox across the same meridian. It is 23 h, 56 m, 4.091 s of mean solar time. The sidereal day is defined to begin at sidereal noon. The time it takes for the Earth to rotate once relative to the stars is longer than the sidereal day by about 0.008 s due to the effect of the precession of the equinoxes.

 

sidereal month

The time it takes for the Moon to complete one orbit of the Earth relative to the stars. This is equal to 27.32166 sidereal days.

 

sidereal period

The interval between two successive positions of a celestial body in the same point with reference to the fixed stars.

 

sidereal time

Time measured by considering the rotation of the Earth relative to the distant stars (as opposed to civil time relative to the Sun). The sidereal time at any instant is the same as the right ascension of objects exactly on the meridian.

 

sidereal year

The interval between two successive passages of the Sun in its apparent annual motion through the same point relative to the stars. It is equal to 365.25636 days, slightly longer than the tropical year due to the effects of the annual precessional motion of the equinox.

 

sigma-t

A conventional definition introduced into physical oceanography for purposes of brevity. It is the remainder of subtracting 1000 kg m from the density of a sea water sample at atmospheric pressure, i.e.

where S and T are the in situ salinity and temperature. The density of water ranges from 1000 kg/m3 to about 1028 kg m for the densest ocean surface water, so sigma-t ranges from about 0.00 to 28.00, with the units usually omitted.

 

sigma-

A measure of the density of ocean water where the quantity sigma-t is calculated using the potential temperature rather than the in situ temperature, i.e.

where S is the in situ temperature.

 

siliceous ooze

A fine-grained sediment of pelagic origin found on the deep-ocean floor. It contains more than 30% siliceous material of organic origin and is usually found below the carbon compensation depth at depths greater than 4500 m. Two types of this are radiolarian oozes and diatom oozes

 

siliclastic

A sediment consisting of particles composed of silicate minerals and rock fragments. Examples are mudstones and sandstones.

 

SILMU

Acronym for the Finnish Research Program on Climate Change, more about which can be found at the SILMU Web site.

 

Silurian

The third period of the Paleozoic era, lasting from 438 to 408 Ma. It precedes the Devonian period and follows the Ordovician period, and is comprised of the Early (438-421 Ma) and Late (421-408 Ma) epochs. It is named for the Silures, and ancient Celtic tribe of the Welsh borderland and the strata contain the first jawed fish as well as abundant trilobites, brachiopods, and crinoids.

 

simoom

A hot, dry, suffocating wind or whirlwind that occurs in the deserts of Africa and Arabia. It is most frequent in spring and summer, usually carries much sand, is short-lived (around 20 minutes), and can change the shape of the sand dunes along its track.

 

Singular Spectrum Analysis

A method of time series analysis, sometimes abbreviated as SSA, designed to extract as much information as possible from short, noisy time series without prior knowledge of the dynamics underlying the series. It is a form of Principal Component Analysis applied to lag-correlation structures of time series. It was developed by Broomhead and King (1986) and applied to the analysis of paleoclimate time series by Vautard and Ghil (1989) and Vautard et al. (1992). The SSA Toolkit includes SSA amongst several time series analysis tools.

SSA performs better than traditional Fourier analysis at separating closely spaced relevant spectral peaks, but retains problems such as the requirement of stationarity and the limitation to situations of high SNRs. See Ruiz de Elvira and Bevia (1994).

 

SIO

Abbreviation for Scripps Institution of Oceanography.

 

SIR-C

Acronym for the Shuttle Imaging Radar-C used for geologic, hydrologic, and oceanographic studies. It can image the Earth through cloud cover and its sensitivity to surface roughness, soil moisture, and sea-ice-water contrast makes it useful in studies of geological features, canopy morphology, sea-ice dynamics, and ocean surface temperature. See the SIR-C Web site.

 

sirocco

See scirocco.

 

SISMER

Acronym for Systemes d'Informations Scientifiques pour la Mer or, in translation, the French National Oceanographic Data Center. See the SISMER Web site.

 

SIW

In physical oceanography, a water mass type. See Tomczak and Godfrey (1994), p. 161.

 

Six thermometer

A self-registering maximum and minimum thermometer invented by James Six (1731?-1793) of England in 1782. It consisted of a U-shaped tube with mercury in the bend, one side filled with alcohol, and the other partially filled. Indices marked the highest and lowest temperatures. This was the most widely used thermometer for taking deep sea temperatures up until the 1870s. See Deacon (1971).

 

Skagerrak

A circulation controlled sedimentary basin that provides part of the connection (along with Kattegat) between the North Sea and the Baltic. It is surrounded by Norway to the northwest, Sweden to the northeast, Denmark and Kattegat to the southeast, and the North Sea to the southwest. It is centered at approximately 9 deg. E and 58 deg. N and is the deepest part (> 700 m) of the the Norwegian Trench.

The circulation in Skagerrak is counterclockwise with North Sea water masses entering via the Jutland Current in the southwest, proceeding northeastward along the Denmark coast, combining with some of the brackish Baltic Current, turning and flowing northwestward along Sweden, turning again and becoming the Norwegian Coast Current (NCC) as it flows southwestward along Norway, and finally leaving Skaggerak and turning northwards as the NCC. There is also a deep countercurrent beneath the NCC that injects high salinity Atlantic water into the Skagerrak deep. See Svansson (1975).

 

skin effect

A temperature inversion in a thin near-surface ocean layer with a thickness of several millimeters. This is a source of uncertainty in radiometric measurements. The inversion layer, created mainly by evaporation, results in an underestimation of the SST compared with what it would be as determined by conventional methods in a layer with a thickness ranging from several tens of centimeters to several meters. See Kagan (1995).

 

skin temperature

In modeling land surface processes, this refers to the effective radiating temperature of the soil plus canopy surface. It is inferred from satellites in the 8-12 m window region. In climate models, it is the temperature used to determine upward thermal emission. A model without vegetation would use the temperature of the top soil surface as the skin temperature, while one with vegetation would use an average of the soil and canopy temperatures weighted according to the vegetation cover. The skin temperature thus defined usually shows a larger diurnal variation than the surface air temperature, a factor that needs to be considered when considering data/model comparisons. See Dickinson (1992).

 

slab ocean

A simple, non-dynamic ocean model used in coupled model simulations. SSTs are calculated from surface energy balance and heat storage in a fixed-depth mixed layer but there are no ocean currents, i.e. we account for the effects of local and temporal but not non-local processes. The salient equilibration time of this type of model is that of the slab ocean, usually on the order of about 20 years for a 50 m thick slab.

 

Slepian sequences

The name given to the data windows used in the Multiple Window Method (MWM) method for the analysis of time series. Named after David Slepian, the first to describe their properties for the purposes of time series analysis, they are also known (more technically) as discrete prolate spheroidal sequences. A tutorial on their use in the MWM as well as applications thereof to paleoclimate time series can be found in Thomson (1990a).

 

slippery sea

A phenomenon occurring in the wind-driven layer at the surface of the sea. In conditions of strong surface heating, a well-mixed warmer (and lighter) layer if formed, which is of limited depth because the stabilizing density distribution inhibits vertical mixing with the deeper, colder water. At the bottom of this surface layer is a strong density gradient where the turbulence is suppressed and the Reynolds stresses are small. A given wind stress at the surface can thus accelerate the water to produce stronger surface currents in this case compared to an unstratified ocean. This is true because both the depth of the layer involved is smaller and the retarding stress below it is reduced. This creates the slippery sea phenomenon. See Turner (1973).

 

slow manifold

A hypothetical N-dimensional manifold (i.e. surface) embedded in the 3N-dimensional phase space of a primitive equation model that is devoid of gravity waves. This has been called the Holy Grail of initialization schemes for weather forecasting since if a numerical weather prediction model could be initialized with observations filtered to retain just their components on the slow manifold, then the large-amplitude gravity waves that have wrecked numerical forecasts since Richardson would no longer be a problem. The concept was introduced by Leith (1980) and is reviewed by Boyd (1995).

 

SLP

Abbreviation for sea level pressure.

 

SMM

Abbreviation for Solar Maximum Mission.

 

SMMR

Abbreviation for Scanning Multichannel Microwave Radiometer, an instrument that has been on board both SEASAT and NIMBUS-7. It produced earth location and time-tagged SSTs, surface wind stress, atmospheric water vapor, liquid water content, and precipitation rate information. See Liu (1984).